The present invention relates to automatic and remote meter reading systems of the type used in the utility industry. In particular, the invention relates to radio frequency (xe2x80x9cRFxe2x80x9d) systems used to communicate with metering devices so that utility consumption can be determined from a remote location.
As is well known, utility industries (such as gas, electricity and water) typically install a meter to indicate consumption by a particular customer. The consumption indicated by the meter forms the basis of the bill sent to the customer each month (or over another predetermined period of time). To read consumption from the meter, the utility industries have often utilized personnel whose job has been to physically inspect meters at each customer location.
In order to reduce the need for meter-reading personnel to inspect every meter, many utilities have begun using various automatic meter reading (xe2x80x9cAMRxe2x80x9d) and remote meter reading (xe2x80x9cRMRxe2x80x9d) systems. These systems simplify the meter-reading process, by reading usage information from the individual meters through RF transmission. Toward this end, each of the meters will include a meter interface unit (xe2x80x9cMIUxe2x80x9d) that controls transmission of usage information read from the meter. At a predetermined scheduled time or upon receipt of an electronic request, the MIU will send the usage information via a predetermined RF format. Examples of MIU devices of the prior art are shown, for example, in U.S. Pat. Nos. 5,553,094 and 4,839,642. Each of these patents is incorporated herein by reference.
In the past, it has often been necessary to provide a dedicated MIU device for the particular meter encoder with which it will be utilized. For example, water meters may be equipped with one of a number of different types of meter encoders. In addition, a particular usage location may contain several meter encoders networked together to provide compound, or multiple, registers. Thus, it was often necessary to determine which of any number of MIU devices was required in a particular application.
In addition, certain older meter encoders have been considered to be generally incompatible with newer electronics technology. For example, older meter encoders often require voltage levels of 5 volts or greater in order to read usage information. In contrast, modern integrated circuits operate effectively at lower voltage levels, typically 3.6 volts or less. In addition, to limit the need for battery replacement, it is desirable to conserve battery power whenever possible.
The present invention recognizes various disadvantages of prior art constructions and methods. Accordingly, it is an object of the present invention to provide novel arrangements for the construction of a utility meter interface unit.
It is a further object of the present invention to provide a meter interface unit that can be used with a variety of meter encoder types.
It is a further object of the present invention to provide a meter interface unit operating at a lower voltage level than the meter encoder, while employing a lower voltage power source.
It is a further object of the present invention to provide a meter interface unit which effectively conserves power during times when usage information is not being determined.
It is a further object of the present invention to provide a meter interface unit which can supply a selected clock signal depending on the type of encoder.
Some of these objects are achieved by a utility meter interface unit for use with a meter encoder. The unit comprises a transmitter operative to send usage information obtained from the meter encoder to a remote location. A processor is operative to initiate reading of usage information from the meter encoder and to control transmission thereof. Power management circuitry responsive to the processor is also provided. The power management circuitry is operative to direct power from a power source to the meter encoder only at selected times such that power is conserved during periods when the usage information is not being read.
In some exemplary embodiments, voltage from the power source is modulated by the power management circuitry and supplied to the meter encoder at a predetermined frequency. Preferably, the processor may be operative to identify the meter encoder and responsively adjust the predetermined frequency based thereon. For example, the processor may be operative to read the usage information from both single and compound register encoders.
In addition, the device may read usage information from networks of multiple meter encoders. In such applications, multiple encoders may read using a multiplicity of data lines while employing a common clock signal.
Often, the power management circuitry will include step-up circuitry operative to step-up a source voltage supplied by the power source to a predetermined higher voltage level. In some exemplary embodiments, the step-up circuitry may include a storage capacitor for maintaining the predetermined higher voltage level. A selectively conducting arrangement, such as at least one transistor, may be connected in circuit with the storage capacitor. In such embodiments, the selectively conducting arrangement is controlled to switch at the predetermined frequency. Often, it will be desirable for the step-up circuitry to include an inductor connected in circuit with a diode to supply charging current to the storage capacitor.
Other objects of the present invention are achieved by a utility meter interface unit for use with a meter encoder which comprises a transmitter operative to send usage information obtained from the meter encoder to a remote location. A processor is operative to initiate reading of the usage information from the meter encoder and store data representative thereof in a memory. The processor is further operative during reading of the usage information to identify the meter encoder from among at least two known encoder types. The processor is also operative to control transmission of the usage information utilizing a predetermined transmission protocol.
In some exemplary embodiments, the processor is operative to effect a different clock frequency to be supplied to the meter encoder depending on which type of known encoder is identified. For example, a first of the known encoder types may be a single register encoder and a second of the known encoder types may be a compound register encoder. Depending on the type, the predetermined frequency may be either approximately 1200 hertz or approximately 19.2 kilohertz in some exemplary embodiments.
Often, the meter interface unit may comprise a battery and power management circuitry responsive to the processor. In such embodiments, the power management circuitry is operative to direct power from the battery to the meter encoder only at selected times such that battery power is conserved during periods when the usage information is not being read. Often, the power management circuitry will be operative to modulate voltage from the battery and supply the modulated voltage to the meter encoder at the predetermined frequency. In addition, the power management circuitry may include step-up circuitry operative to step-up a battery voltage supplied by the battery to a predetermined higher voltage level.
Still further objects of the present invention are achieved by a meter interface unit for use with a meter encoder requiring a predetermined encoder voltage level. The unit comprises a power source supplying a source voltage level less than the encoder voltage level. A transmitter is operative to send usage information obtained from the meter encoder to a remote location. A processor is also provided, operative to initiate reading of the usage information from the meter encoder and to control transmission thereof. Power management circuitry responsive to the processor is also provided. The power management circuitry includes step-up circuitry operative to step-up the voltage level supplied by the power source to at least the encoder voltage level.
Additional objects of the present invention are achieved by a method of reading usage information from a utility meter encoder. One step of the method involves supplying power to the encoder at a first predetermined frequency. Based on information responsively supplied by the encoder, it is verified whether the encoder is of a first known type. If the encoder is not of the first known type, power is supplied to the encoder at a second predetermined frequency. Based on information responsively supplied by the encoder, it is then verified whether the encoder is of a second known type. Usage information from the encoder is read and appropriately stored. The usage information is then transmitted to a remote location for further use as necessary.
Often, the first known type of encoder may be a single register encoder, and the second known type of encoder may be a multiple register encoder. When the encoder is of the second known type, usage information from each of the multiple registers may be successively read and stored. According to exemplary methodology, the first predetermined frequency may be approximately 1200 hertz and the second predetermined frequency may be approximately 19.2 kilohertz. Often, it will be desirable to convert usage information received from the meter encoder in a first format to a second format prior to transmission thereof.
Other objects, features and aspects of the present invention are provided by various combinations and subcombinations of the disclosed elements, as well as methods of practicing same, which are discussed in greater detail below.